<s>
Within	O
data	B-Application
modelling	I-Application
,	O
cardinality	B-Application
is	O
the	O
numerical	O
relationship	O
between	O
rows	O
of	O
one	O
table	O
and	O
rows	O
in	O
another	O
.	O
</s>
<s>
Common	O
cardinalities	B-Application
include	O
one-to-one	O
,	O
one-to-many	O
,	O
and	O
many-to-many	O
.	O
</s>
<s>
Cardinality	B-Application
can	O
be	O
used	O
to	O
define	O
data	O
models	O
as	O
well	O
as	O
analyze	O
entities	O
within	O
datasets	O
.	O
</s>
<s>
For	O
example	O
,	O
consider	O
a	O
database	O
of	O
electronic	B-Application
health	I-Application
records	I-Application
.	O
</s>
<s>
In	O
data	B-Application
modeling	I-Application
,	O
collections	O
of	O
data	O
elements	O
are	O
grouped	O
into	O
"	O
data	O
tables	O
"	O
which	O
contain	O
groups	O
of	O
data	O
field	O
names	O
called	O
"	O
database	O
attributes	O
"	O
.	O
</s>
<s>
Computer	O
scientist	O
Edgar	O
F	O
.	O
Codd	O
created	O
a	O
systematic	O
method	O
to	O
decompose	O
and	O
organize	O
relational	B-Application
databases	I-Application
.	O
</s>
<s>
Codd	O
's	O
steps	O
for	O
organizing	O
database	O
tables	O
and	O
their	O
keys	O
is	O
called	O
database	B-Application
normalization	I-Application
,	O
which	O
avoids	O
certain	O
hidden	O
database	O
design	O
errors	O
(	O
delete	B-Application
anomalies	I-Application
or	O
update	B-Application
anomalies	I-Application
)	O
.	O
</s>
<s>
In	O
real	O
life	O
the	O
process	O
of	O
database	B-Application
normalization	I-Application
ends	O
up	O
breaking	O
tables	O
into	O
a	O
larger	O
number	O
of	O
smaller	O
tables	O
.	O
</s>
<s>
In	O
the	O
real	O
world	O
,	O
data	B-Application
modeling	I-Application
is	O
critical	O
because	O
as	O
the	O
data	O
grows	O
voluminous	O
,	O
tables	O
linked	O
by	O
keys	O
must	O
be	O
used	O
to	O
speed	O
up	O
programmed	O
retrieval	O
of	O
data	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
data	B-Application
modeling	I-Application
is	O
a	O
keystone	O
in	O
the	O
skills	O
needed	O
by	O
a	O
modern	O
software	O
developer	O
.	O
</s>
<s>
The	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
model	I-Architecture
proposes	O
a	O
technique	O
that	O
produces	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
diagrams	I-Architecture
(	O
ERDs	O
)	O
,	O
which	O
can	O
be	O
employed	O
to	O
capture	O
information	O
about	O
data	O
model	O
entity	O
types	O
,	O
relationships	O
and	O
cardinality	B-Application
.	O
</s>
<s>
In	O
the	O
object-oriented	O
application	O
programming	O
paradigm	O
,	O
which	O
is	O
related	O
to	O
database	O
structure	O
design	O
,	O
UML	B-Language
class	O
diagrams	O
may	O
be	O
used	O
for	O
object	O
modeling	O
.	O
</s>
<s>
In	O
that	O
case	O
,	O
object	O
relationships	O
are	O
modeled	O
using	O
UML	B-Language
associations	O
,	O
and	O
multiplicity	O
is	O
used	O
on	O
those	O
associations	O
to	O
denote	O
cardinality	B-Application
.	O
</s>
